1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
|
// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_MESSAGE_PUMP_LIBEVENT_H_
#define BASE_MESSAGE_PUMP_LIBEVENT_H_
#include "base/message_pump.h"
#include "base/scoped_ptr.h"
#include "base/time.h"
// Declare structs we need from libevent.h rather than including it
struct event_base;
struct event;
namespace base {
// Class to monitor sockets and issue callbacks when sockets are ready for I/O
// TODO(dkegel): add support for background file IO somehow
class MessagePumpLibevent : public MessagePump {
public:
// Object returned by WatchFileDescriptor to manage further watching.
class FileDescriptorWatcher {
public:
FileDescriptorWatcher();
~FileDescriptorWatcher(); // Implicitly calls StopWatching.
// NOTE: These methods aren't called StartWatching()/StopWatching() to
// avoid confusion with the win32 ObjectWatcher class.
// Stop watching the FD, always safe to call. No-op if there's nothing
// to do.
bool StopWatchingFileDescriptor();
private:
// Called by MessagePumpLibevent, ownership of |e| is transferred to this
// object.
// If this FileWatcher is already watching an event, the previous event is
// terminated and cleaned up here.
void Init(event* e, bool is_persistent);
friend class MessagePumpLibevent;
private:
bool is_persistent_; // false if this event is one-shot.
scoped_ptr<event> event_;
DISALLOW_COPY_AND_ASSIGN(FileDescriptorWatcher);
};
// Used with WatchFileDescptor to asynchronously monitor the I/O readiness of
// a File Descriptor.
class Watcher {
public:
virtual ~Watcher() {}
// Called from MessageLoop::Run when an FD can be read from/written to
// without blocking
virtual void OnFileCanReadWithoutBlocking(int fd) = 0;
virtual void OnFileCanWriteWithoutBlocking(int fd) = 0;
};
MessagePumpLibevent();
virtual ~MessagePumpLibevent();
enum Mode {
WATCH_READ,
WATCH_WRITE,
WATCH_READ_WRITE
};
// Have the current thread's message loop watch for a a situation in which
// reading/writing to the FD can be performed without Blocking.
// Callers must provide a preallocated FileDescriptorWatcher object which
// can later be used to manage the Lifetime of this event.
// Returns true on success.
// TODO(dkegel): switch to edge-triggered readiness notification
bool WatchFileDescriptor(int fd,
bool persistent,
Mode mode,
FileDescriptorWatcher *controller,
Watcher *delegate);
// MessagePump methods:
virtual void Run(Delegate* delegate);
virtual void Quit();
virtual void ScheduleWork();
virtual void ScheduleDelayedWork(const Time& delayed_work_time);
private:
// Risky part of constructor. Returns true on success.
bool Init();
// This flag is set to false when Run should return.
bool keep_running_;
// This flag is set when inside Run.
bool in_run_;
// The time at which we should call DoDelayedWork.
Time delayed_work_time_;
// Libevent dispatcher. Watches all sockets registered with it, and sends
// readiness callbacks when a socket is ready for I/O.
event_base* event_base_;
// Called by libevent to tell us a registered FD can be read/written to.
static void OnLibeventNotification(int fd, short flags,
void* context);
// Unix pipe used to implement ScheduleWork()
// ... callback; called by libevent inside Run() when pipe is ready to read
static void OnWakeup(int socket, short flags, void* context);
// ... write end; ScheduleWork() writes a single byte to it
int wakeup_pipe_in_;
// ... read end; OnWakeup reads it and then breaks Run() out of its sleep
int wakeup_pipe_out_;
// ... libevent wrapper for read end
event* wakeup_event_;
DISALLOW_COPY_AND_ASSIGN(MessagePumpLibevent);
};
} // namespace base
#endif // BASE_MESSAGE_PUMP_LIBEVENT_H_
|
